1. Field of the Invention
This invention relates to copolymers of a mixture of 3-methacryloyloxy-2-hydroxypropyltrimethylammonium halide salt and its isomer, 2-methacryloyloxy-3-hydroxypropyltrimethylammonium halide salt, and other vinyl monomers. Preferably, the present invention provides copolymers of a mixture of 3-methacryloyloxy-2-hydroxypropyltrimethylammonium chloride and its isomer, 2-methacryloyloxy-3-hydroxypropyltrimethylammonium chloride, collectively known as MAHTAC, and other vinyl monomers.
2. Description of the Prior Art
The flocculation activity of copolymers of acrylamide and monomers containing cationic, quaternary nitrogen functionality has long been known and a wide body of literature covering the synthesis of cationic monomers and polymers exists, and in particular emulsion polymerization techniques leading to copolymers of acrylamide and these monomers. In particular, U.S. Pat. Nos. 3,284,393; 3,321,649; 3,329,706; 3,428,617; 4,077,930; 4,217,262; and Vanderhoff, J. W., et al., "Inverse Emulsion Polymerization". Polymerization and Polycondensation Processes, Advances in Chemistry Series 34, (1962), teach copolymers and the preparation thereof.
Acrylamide-MAHTAC copolymers are disclosed in U.S. Pat. Nos. 3,329,706 and 3,428,617. The polymers mentioned were taught to be particularly useful as additives to paper products to enhance properties such as wet strength and abrasion resistance. Activity in flocculation of biologically treated wastes was not disclosed. The references give several examples of the synthesis of copolymers of acrylamide and MAHTAC wherein the copolymers have an intrinsic viscosity range of 0.9 to 2.8 dl/g. This viscosity range corresponds to a molecular weight range that is too low to provide flocculation activity competitive with copolymers of acrylamide and common, commercially available monomers, such as acryloyloxyethyltrimethylammonium chloride, which are produced by conventional transesterification synthesis routes.
U.S. Pat. No. 3,321,649 teaches a flocculating agent of a mixture of (a) a water soluble cationic polymer of 3-methacryloyloxy-2-hydroxypropyltrimethylammonium chloride and a dissimilar monomer having at least one ethylenic linkage, and (b) a polyacrylamide. Although the reference teaches that water soluble cationic polymers with an intrinsic viscosity of about 0.5 to 10 dl/g are desirable, the highest intrinsic viscosity for a copolymer (Example 1) is only 2.8 dl/g.
U.S. Pat. Nos. 4,077,930 and 4,217,262, cite the MAHTAC monomer as being suitable for use in formulations intended for flocculation applications. However, there are no specific examples where this particular monomer is actually used and this monomer is not currently commercially available.
It would be desirable to have MAHTAC based copolymers wherein the viscosity of the copolymers is higher than that of known products having MAHTAC therein so that they may be used as flocculants in waste water treatment applications.
As such, the present invention fulfills the need in the art for MAHTAC based copolymers wherein the viscosity of the copolymers is higher than that of known products.
Other advantages of the present invention will become apparent from the following description, attached drawings and appended claims.